Needle stabilizer for sewing machines



Feb- 16 1954 B. P. PINKvoss ET AL 2,669,206

ATTRNE Y Feb 16 1954 B. P. PlNKvoss E-r AL l 2,669,206

' NEEDLE STABILIZER FOR SEWING MACHINES Filed D90. 15,-1951 2Sheets-Sheet 2 A'ITRNEY Patented Feb. 16, I1954 NEEDLE STABILIZER FORSEWING MACHINES Berthold P. Pinkvoss, Stratford, and Stanley J.Ketterer, Bridgeport, Conn., assignors to The Singer ManufacturingCompany,

Elizabeth,

N. J., a corporation of New Jersey Application December 15, 1951, SerialNo. 261,778

Claims.

This invention relates to needle stabilizing devices for a sewingmachine and particularly to a needle stabilizing arrangement adapted foruse with a sewing machine having either a freely rotatable presser-wheelor a driven work-feeding presser-wheel. It is an object of thisinvention to provide a needle stabilizer which is effective accuratelyto -guide the point of a slender needle to the desired stitch line witha minimum of frictional drag or lbending of the needle, therebyprolonging the useful life of the needle.

. When stitching a, straight seam in a material such as leather, it isfrequently desirable to guide ithe needle point to the work, therebyovercoming the effect, for instance, of needle vibration due to the useof a relatively slender needle. One highly efficient type of needlestabilizer construction involves the use of an Lunyielding needleguiding surface arranged at a sharp angle with the needle bar andagainst which the needle point glances so as to be cammed into properwork penetration position. As an example, the patent to Knox, No.1,864,136, June 2l, 1932, discloses this type` of needle stabilizer inwhich the needle guiding surface is formed asv an integral part of rtheroller presser.

In the various embodiments of that described type of needle stabilizerconstruction,` the needle -guiding surfaces are firmly supported tolprevent .movement thereof laterally of the line of stitch formation.Apparently it was felt that the needle point must be cammed into properposition in the most positive manner. As a result, considerable frictionis developed between the needle blade and the guiding surface, whichfriction has a detrimental effect on the needle. In the Knoxconstruction, an attempt was made to alleviate this objectionableexcessive friction by inclinf ing the needle from the vertical so that,in theory,

only the needle point would touch the guiding surface formed on thepresser roller. In practice, however, it has been observed that withcertain types of materials the needle, after penetration of the work,isdrawn laterally in the direction of the presser roller thus causingincreased friction therebetween. The consequent effect of such excessivefriction is detrimental to the life of the needle and in certaininstances vvresults in an objectionable permanent bend in the needleblade.

l We have found that absolute rigidity of the needle stabilizer againstmovement laterally of #the line of Vstitch formation is not essential tosatisfactory needle positioning but, on the contrary, a considerableamount of flexibility is permissable. With a. somewhat flexible needlestabilizer, it becomes apparent that the action of the stabilizer uponthe slender needle point is more in the nature of a parrying than acamming action. Accordingly, we provide in the present invention, aneedle stabilizer which is yieldable laterally of the line of stitchformation. In normal unflexed position, the stabilizer extends acrossthe axis of the needle bar and it is spaced suiciently from thesurrounding objects so that movement is permissable to compensate forthe above described lateral drawing effect. With this fiexiblestabilizer, the frictional `drag between the needle blade and thestabilizer is substantially constant depending in amount primarily uponthe flexibility of the stabilizer.

Other objects and advantages will appear from the followingspecification and the accompanying drawings which illustrate thepreferred embodiment of our invention and in which:

Fig. 1 represents a longitudinal sectional View of a. portion of asewing machine to which the invention is applied and taken in a verticalplane passing substantially through the needle.

Fig. 2 is an end elevational View, partly in section, of the portion ofthe sewing machine illustrated in Fig. 1 with the end cover platesremoved.

Fig. 3 is an enlarged front elevation View, partly in cross section, ofthe rearward presser and needle stabilizer o-f Figs. l and 2, with thead- .jacent parts illustrated fragmentarily.

Fig. 4 is an enlarged fragmentary view of that portion of the rollerpresser and needle stabilizer of Fig. 3 adjacent the work, and in whichthe needle and the stabilizer are illustrated in three differentpositions during a typical cycle of stitch formation.

Fig. 5 is a front elevational view partly in cross section and similarto Fig. 3, but showing a modied form of roller presser and needlestabilizer.

The selected embodiment the invention is i1- lustrated as applied to alock stitch post machine which comprises a frame of which a verticallyarranged work supporting post Il and an over# hanging bracket-arm I2 areillustrated. Rotatlably journaled in the post Il, is a hook shaft I4 towhich a rotary hook l5 is secured, and a feed driving shaft I6 which isconnected by bevel gears I'I-II to a lower feed wheel I8. The hook shaftI4 is driven in the usual continuous fashmittently in one direction by asuitable driving arm I2 and is operatively connected for endwise`reciprocatory movement by means of a driving link 26 and a crank 21 faston a rotary shaft 28 arranged Within the bracket-arm. Also endwiseslidably journaled in a bracket-arm l2 is a presser-bar 30 to the lowerextremity ofwhich'is i secured a supporting arm 3l-for. an inclinedstudi shaft I32. A portion of the stud-shaft is threaded. as at 33, andis formed on the unthreaded extremity with a conical ball bearing race34:l Engaging the stud shaft threads 33 is a bearing conning member 35having a second conical ball bearing race 36 formed thereon. The studshaft 32 is rigidly secured to the arm 3| by a clamp .arrangementbetween the bearing coni-lning member 35 and a fastening nut 3T.. Adriven presser wheel 38 which Lis rotatably journaled on the stud shaft32 by means of bearing balls 39--39\, is provided with a knurledperipheral portion 4i! which is arranged above the lower `feed wheel I8.The slight inclination of the stud shaft 32 and consequently of thepresser-wheel -38 provides clearance forthe needle bar and permits thepresser wheel to be disposed nearer to the needle path. Integral withthe presser wheel 38 is a pulley 4| which is engaged by an endless belt42 connecting the presser wheel with the feed wheel drive shaft IBthroughsuitable connectons (not shown) .in'the machine frame.

Referring to Figs. 3 and 5, the needle stabilizer, indicated generallyas 50, is carried by the presser device. The stabilizer isV preferablyfabricated of sheet metal in the form of a dish-shaped circular disk.More particularly, the stabilizer is formed with a hat central portion iwhich denes a single plane. 'The flat centraly portion merges into agenerally irusto-conical marginal portion 52 and of which an outerperipheral rim 53 is bent into a plane vsubstantially parallel to l'theplane of the flat central portion 5l.

k'ner in which the stabilizer is secured tothe presser device. Ineachconstruction, however, the stabilizer is inclined vfrom the verticalbecause of the inclination of the stud shaft '32 and vpresser wheel 38.YIn Fig. 3, the stabilizer is fastened at its' lcenter to the freel endof the stud 'shaft 32 by means of a single fastening kscrew 60 which isthreaded into a hole formed centrally of the stud shaft.` lThe shape ofthe marginal portion 52 and Vtherinr 53 ofthe stabilizer is generallysimilar to that yof theadjacent` face 44 of "the presser wheel, andconsequently the space between the stabilizer and the face'44 isavailable f to .permitmaximum freedom of nexiblity of the 4 rim 53without contact between the stabilizing disk and the face 44. Thepresser wheel 38 of Fig. 3 is preferably provided with a shallow angularrecess 43 in order to provide additional clearance for flexing of thestabilizer. The stabilizer of Fig. 3 therefore, remains locked againstturning as does the stud shaft 33. By means of the fastening screw G0,however, the stabilizer may be readily loosened and turned to a newangular position to present a fresh face to the needle in case of wear.

In Fig. 5 a construction is illustrated in which the stabilizer issecured to a portion of the adjacent face 44 of the presser wheel andtherefore, rotates with the presser wheel so that the rim portion ofthestabilizer which is presented to the needle is constantly varied.Preferably a plurality of fastening screws -65 are utilized for thispurpose, each being threaded into the presser-Wheel 33. With thisconstruction, an aperture 54 is provided in the center of thestabilizing disk to provide access to the 'stud-shaft 32 so that thepresser device may be disassembled without removing the stabilizingdisk.

Figs. 3 and e each illustrate the needle 23 in three positions during atypical cycle of needle reciprocation. In each iigure, the uppermostposition illustrates the needle kduring that portion of the cycle inwhich it is raised free of the Work 4and the stabilizer; theintermediate or central position illustrates the :needle during initialpenetration of the work W; and the lowermost position illustrates theneedle as it begins to rise. In Fig. 3 the intermediate or centralneedle position is illustrated in solid lines and the rim 53 of thestabilizer 53 is shown in the position which it will occupy as thelneedle initially penetrates the work, while the upper and lowermostneedle positions are illustrated in dotted lines.

In Fig. 4 the uppermost illustrated position of the needle`23 is shownin solid lines as is the corresponding unflexed position of the needlestabilizer rim 53. The central position of the needle 23' in Fig. 4 isillustrated in dotted lines as is the corresponding position of thestabilizer rim 53. In striking the stabilizer rim prior to penetrationof the work, the point `of the needle is shifted or parried slightly tothe right as exaggerated 'slightly in Fig. 4, in the interest ofclarity. A

corresponding shiftl of the stabilizer rim occurs in the oppositedirection. The slight shifting of theneedle under control of thestabilizer has been found to be generally suilicient to eliminateobjectionable vibration `which may exist in the slender needle, andaccurately to position the needle point just as it enters the Work toinsure straight seam formation. In Fig. 4, the lowermost position oftheneedle, which represents the position of the needle as it begins itsupward movement.- is shown in dot-and-dash lines. Similar lines havebeen used to illustrate the corresponding position of the stabilizer rim53. As this -dot-and-dashiline position illustrates, the needle -isdrawn laterally toward the cooperating lower feed-wheel and thepresser-wheel 38 by the action of the work on the needle, which lateraldrawing effect has lbeen found to occur when certain leathers are beingstitched. The flexible needle stabilizer is yieldableto accommodate such-lateralshifting ofthe "needle, kand since suiiicient presser-wheel, thefrictional forces between the needle blade andthe stabilizer remain atla very low and unobjectionable value. It will be obvious that if theneedle stabilizer was inflexible, the a-ction of the work tending tomove the needle laterally toward the roller presser would increase theforce with which the needle is pushed or pulled laterally against theinflexible stabilizer. Such in-creased friction, it has been found, issufficient permanently to bend the needle out of its normally straightform, resulting in a short life of the needle.

I-Iaving thus set forth the nature of the invention, what we claimtherein is:

1. A needle stabilizer for a sewing machine having a presser-mechanismincluding a presserwheel and means supporting said presser-wheeladjacent the path of said needle, comprising a flexible needledeilecting disk adapted to be carried by said presser-supporting means,a rim portion on said disk formed to extend in spaced relation to saidpresser-Wheel and in the path of said needle.

2. In a sewing machine having an endwise reciprocatory needle and workfeeding mechanism including opposed work engaging members, a dish-shapedneedle stabilizing disk open toward the needle and having a flexible rimportion disposed for engagement by said needle at the needle penetratingside of the work.

3. In a sewing machine having a vertically reciprocable needle and aWork feeding mechanism including opposed Work engaging members, avertically inclined needle stabilizing disk supported by one of saidopposed work engaging members, said disk having a flexible rim disposedfor engagement by said needle.

4. In a sewing machine, stitch-forming mechanism including `a needlereciprocable in a vertical path, opposed work-engaging wheels disposedat one side of said needle path, and a flexible needle stabilizing disksupported -coaxially with one of said wheels, said disk having a rimportion arranged in laterally spaced relation to said coaxial Wheel andextending into the path of said needle.

5. A needle stabilizer for a sewing machine having an endwisereciprocable needle, a feed mechanism and a presser mechanism includinga presser-wheel, comprising a sheet metal disk having a, flat centralportion, means associated with said central portion for fastening saiddisk to said presser mechanism in coaxial relation with saidpresser-wheel, said disk having a frusto conical marginal portionjoining said central portion, and a rim formed on the periphery of saidfrustoconical portion, said rim being disposed in a plane substantiallyparallel to said central portion and extending into the path of needlereciprocation.

6. In a sewing machine having an endwise reciprocating needle barandwork feeding mechanism including opposed work engaging members, a.needle stabilizing disk carried by said work feeding mechanism, saiddisk having a flexible rim extending into the path of needlereciprocation, and means providing for selective positioning of any ofportion of said rim in the path of the needle.

7. In 'a sewing machine having an endwise reciprocating needle bar andwork feeding mechanism including opposed work engaging members, a needlestabilizing disk carried by said Work feeding mechanism, said diskhaving a flexible rim disposed for engagement by said needle, and

means eifective upon operation of the machine for constantly varying therim portion of said disk engaged by said needle.

8. In a sewing machine having an endwise reJ ciprocatory needle, a feedmechanism, and a presser mechanism including a presser-bar, a stud-shaftcarried by said presser bar, and a presser wheel journaled on said studshaft, a needle stabilizer comprising a sheet metal disk, fasteningmeans securing said stabilizer disk to said stud-shaft in spacedrelation to said presserwheel, said disk having a rim portion extendinginto the path of needle reciprocation.

9. In a sewing machine having an endwise reciprocatory needle, a feedmechanism, and a presser mechanism including a presser-bar, a stud-shaftcarried by said presser-bar, a presserwheel journaled on saidstud-shaft, and means associated with said stud-shaft for retaining saidpresser-wheel in predetermined axial position on said stud-shaft, aneedle stabilizer comprising a sheet metal disk having a central portionarranged in abutting relation with said presser Wheel, said centralportion having an access opening formed therein exposing said presserwheel retaining means, and a rim portion formed on said stabilizer-diskand disposed in spaced relation with said presser-Wheel.

10. A needle stabilizer for a sewing machine having an endwisereciprocable needle, a presser mechanism including a presser-wheel, andmeans supporting said presser-Wheel adjacent the path of reciprocationof said needle, comprising a needle deflecting member adapted to besecured to said presser-mechanism and including -a portion adapted toextend into the path of needle reciprocation in spaced relation to saidpresserwheel, said portion being exible transversely of the axis ofneedle reciprocation.

BERTHOLD P. PINKVOSS. STANLEY J. KETTERER.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 207,230 Wensley Aug'. 20, 1878 400,355 Neely Mar. 26, 1889419,584 Coombs Jan, 14, 1890 1,999,251 Moranville Apr. 30, 1935

